From: Kevin Wolf <kwolf@redhat.com>
Date: Fri, 29 Jun 2012 11:40:27 +0000 (+0200)
Subject: coroutine-ucontext: Help valgrind understand coroutines
X-Git-Tag: TizenStudio_2.0_p2.3.2~208^2~3872^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3f4349dc8b9494315f8331b2ea4e8d1f83fb801d;p=sdk%2Femulator%2Fqemu.git

coroutine-ucontext: Help valgrind understand coroutines

valgrind tends to get confused and report false positives when you
switch stacks and don't tell it about it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/configure b/configure
index 0a3896e..cef0a71 100755
--- a/configure
+++ b/configure
@@ -2871,6 +2871,22 @@ if compile_prog "" "" ; then
 fi
 
 ########################################
+# check if we have valgrind/valgrind.h
+
+valgrind_h=no
+cat > $TMPC << EOF
+#include <valgrind/valgrind.h>
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+int main(void) {
+  VALGRIND_STACK_DEREGISTER(0);
+  return 0;
+}
+EOF
+if compile_prog "" "" ; then
+    valgrind_h=yes
+fi
+
+########################################
 # check if environ is declared
 
 has_environ=no
@@ -3379,6 +3395,10 @@ if test "$linux_magic_h" = "yes" ; then
   echo "CONFIG_LINUX_MAGIC_H=y" >> $config_host_mak
 fi
 
+if test "$valgrind_h" = "yes" ; then
+  echo "CONFIG_VALGRIND_H=y" >> $config_host_mak
+fi
+
 if test "$has_environ" = "yes" ; then
   echo "CONFIG_HAS_ENVIRON=y" >> $config_host_mak
 fi
diff --git a/coroutine-ucontext.c b/coroutine-ucontext.c
index 5f43083..e3c450b 100644
--- a/coroutine-ucontext.c
+++ b/coroutine-ucontext.c
@@ -30,6 +30,10 @@
 #include "qemu-common.h"
 #include "qemu-coroutine-int.h"
 
+#ifdef CONFIG_VALGRIND_H
+#include <valgrind/valgrind.h>
+#endif
+
 enum {
     /* Maximum free pool size prevents holding too many freed coroutines */
     POOL_MAX_SIZE = 64,
@@ -43,6 +47,11 @@ typedef struct {
     Coroutine base;
     void *stack;
     jmp_buf env;
+
+#ifdef CONFIG_VALGRIND_H
+    unsigned int valgrind_stack_id;
+#endif
+
 } CoroutineUContext;
 
 /**
@@ -159,6 +168,11 @@ static Coroutine *coroutine_new(void)
     uc.uc_stack.ss_size = stack_size;
     uc.uc_stack.ss_flags = 0;
 
+#ifdef CONFIG_VALGRIND_H
+    co->valgrind_stack_id =
+        VALGRIND_STACK_REGISTER(co->stack, co->stack + stack_size);
+#endif
+
     arg.p = co;
 
     makecontext(&uc, (void (*)(void))coroutine_trampoline,
@@ -185,6 +199,16 @@ Coroutine *qemu_coroutine_new(void)
     return co;
 }
 
+#ifdef CONFIG_VALGRIND_H
+/* Work around an unused variable in the valgrind.h macro... */
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+static inline void valgrind_stack_deregister(CoroutineUContext *co)
+{
+    VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id);
+}
+#pragma GCC diagnostic error "-Wunused-but-set-variable"
+#endif
+
 void qemu_coroutine_delete(Coroutine *co_)
 {
     CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
@@ -196,6 +220,10 @@ void qemu_coroutine_delete(Coroutine *co_)
         return;
     }
 
+#ifdef CONFIG_VALGRIND_H
+    valgrind_stack_deregister(co);
+#endif
+
     g_free(co->stack);
     g_free(co);
 }